P02AD: Cylinder 5 misfire evidence must be paired with rail-control status

P02AD concerns suspected injector leakage on cylinder 5. The GM table requires both a cylinder-specific combustion problem and a rail-pressure-control minimum error. Treating the code as merely another name for a cylinder 5 misfire would omit half of the diagnostic logic.

The paired observations

The documented counter boundary is more than 100 misfires for cylinder 5. The pressure-control minimum-error status must also be set. Neither a shared rail complaint with no cylinder evidence nor an isolated misfire count fully reproduces this combination.

The monitor has a five-second interval and two-trip reporting. It runs only within the specified engine-speed window above 1,520 and below 6,000 rpm, with relative air charge below 100 percent and no injector electrical failure. Statistical inhibition must also be absent.

Preserve shared and local information

Rail control is shared system evidence; the misfire counter localizes the monitored pattern to cylinder 5. Reviewing both together helps avoid assigning every rail-pressure complaint to this injector. If several cylinders show similar patterns, that broader context should remain visible rather than being discarded after reading one code.

The source supports a failure-open hypothesis, not a confirmed leaking component. Cylinder numbering and the approved confirmation method depend on the actual engine. High-pressure fuel equipment should be evaluated through the appropriate service process; the summary does not support improvised opening, spraying or swapping tests.

Source and applicability

This explanation covers the cited GM monitor, not every vehicle carrying this code. The application-matrix filename does not resolve cleanly to this file, so no model or engine fitment is assigned. GM diagnostic table, PDF page 707.